1. Field of the Invention
This invention relates to a shutter for a disk cartridge and a method for producing the shutter and, more specifically to a shutter which is movably attached to the disk cartridge and has an opening or aperture for exposing at least a portion of the signal recording surface of the disk.
2. Description of the Art
Heretofore, for protecting a disk, such as an optical disk or a magneto-optical disk on which predetermined signals are written, a disk cartridge is employed. Such a disk cartridge is disclosed for example in Japanese Laid-open Patent Nos. 257686/1987 and 61485/1988, wherein the disk cartridge houses the disk and is mounted in position within a recording/reproducing apparatus. The disk cartridge in these Japanese patents is formed by an upper half and a lower half of synthetic resin abutted to each other.
Since the disk cartridge is attached to the recording/reproducing apparatus, in order to house the disk with the cartridge, an opening is formed in each of the opposite planar surfaces of the cartridge. As such, the signal recording surfaces of the disk are exposed along the radial direction and a disk table adapted to drive the disk into rotation can be positioned within the opening. Thus, dust or other contaminants may be introduced into the interior of the cartridge through this opening. Alternatively, during the handling of the disk, cartridge contaminants, such as fats from a fingerprint, may be deposited on the signal recording surface. These contaminants, when deposited on the signal recording surface, may cause dropout of write or read signals at the time of writing and/or reading of information signals.
Thus, a shutter having a U-shaped cross-section is movably fitted and attached so as to lie on both planar surfaces of the cartridge. In this position, the above-noted opening may be closed by the shutter during non-use time when the disk cartridge is not mounted in position within the recording and/or reproducing apparatus.
As disclosed in the U.S. Pat. No. 4,688,206, the shutter is repeatedly moved in connection with the attachment and detachment operation thereof to and from the disk cartridge to thereby open or close the above opening. The shutter is of a size sufficient to cover the opening formed at the transverse center of the cartridge and extends from the center to the front end surface thereof. The shutter has a surface area larger than the surface area of the cartridge. Inasmuch as the shutter is fitted so as to overlie both planar surfaces of the cartridge, the shutter is required to be thin enough to be disposed within the recess formed in each planar surface of the cartridge. This, however, must be accomplished without the shutter projecting from such planar surface, or without increasing the thickness of the cartridge, such that smooth attachment and detachment of the disk cartridge to and from the recording and/or reproducing apparatus is ensured.
That is, it is necessary for the shutter employed in a disk cartridge to have a sufficient mechanical strength even if it is of a smaller thickness. For this reason, the above shutter is made by punching from a thin metal plate, such as stainless steel plate, followed by bending to a U-shaped cross-section.
In making the shutter, it is punched from a metal plate having a smooth surface which has not been subjected to any pre-treatment. For this reason, contaminations deposited become intensified at the time of handling of the disk cartridge. That is, the difference between the gloss proper of the metal plate material and that of the contaminated portions becomes enhanced.
For enhancing the decorative effect of the shutter formed of a metal plate material, it is also known that, the plate surface can be subjected to a so-called hairline processing. This process consists of forming a large number of minute parallel grooves or hairlines on the plate surface. However, in this case, when contaminants are deposited on the shutter surface, the difference in the gloss between the contaminated portions and the uncontaminated portions similarly becomes intensified to detract from the decorative effect associated with hairline processing. Moreover, the hairlines are formed as minute grooves and thus extremely susceptible to being scored.
The flows or scores extending at an angle, including a right angle, with respect to the hairlines, are most noticeable to viewers.
Above all, in the case of a disk cartridge consisting of a cartridge of a synthetic material less susceptible to being scored or contaminated and a shutter of a metallic material being more susceptible to be scored or contaminated, fitted to the cartridge, the overall appearance of the disk cartridge is marred by these scores or contaminants.
The above problem becomes more pronounced with an increase in the diameter of the disk. As the larger the disk diameter, the larger the size of the opening by which the disk is exposed becomes. Accordingly, the size of the shutter adapted for opening or closing the opening is enlarged.
In addition, the shutter formed of a metal material may be corroded starting from the site of the surface scores.
Accordingly, it is an object of the present invention to provide a shutter for a disk cartridge and method for producing a shutter that eliminates the above-noted defects inherent in the prior art.
Another object of the present invention is to provide a shutter for a disk cartridge which is not impaired in appearance by scores or contaminants.
It is yet another object of the present invention to provide a shutter for a disk cartridge which has improved durability through the prevention of corrosion caused by scores or contaminants.
It is a further object of the present invention to provide a shutter for a disk cartridge having improved aesthetic qualities.
It is yet another object of the present invention to provide an improved method for producing a shutter for a disk cartridge which simplifies production of the shutter.
In accordance with an aspect of the present invention, a shutter for a disk cartridge and method for producing the same is provided wherein the cartridge accommodates a disk and is formed within an opening exposing at least a portion of the signal recording surface of said disk. The shutter is movably attached to said cartridge and a pair of cover plates adapted for opening or closing said opening and a connecting plate interconnecting said cover plates.
A coating is applied at least to the surface of the cover plates having a property which enhances the reflectivity of the shutter surface.
According to the present invention, flaws or contaminants caused by fats from fingerprints deposited on the disk become less prominent by the application of the above-described coating to the surface of the cover plates of the shutter. Additionally, with the application of this coating, corrosion is prevented from occurring at the contaminated portions of the disk.
The above and other objects, features, and advantages of the present invention will become apparent from the following illustrative embodiments thereof to be read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements and parts.